Home School Life Journal

Home School Life Journal

"Let us strive to make each moment beautiful."

Saint Francis DeSales

painting by Katie Bergenholtz

Introduction to Biology

The four criteria for life:1. All life forms contain deoxyribonucleic acid (DNA).2. All life forms have a method to extract energy from their surroundings and convert it into energy that is useful to them.3. All life forms can sense changes in their surroundings and respond to those changes.4. All life forms reproduce..Classifying Living Things

Living things can be classified into one of five kingdoms. Each kingdom can then be further classified into a phylum. Each of the phyla can be further classified into a class. Each class can be further divided into an order. Each order can be further divided into a family. Each family can be further divided into a genus, and each genus can be further divided into a species.

The first and most basic way of dividing organisms is based on whether they have prokaryotic or eukaryotic cells. Prokaryotic cells are not "membrane-bound." The DNA strand, which is a single circular strand, is not bound inside a nucleus but is simply suspended in the cytoplasm. The Eukaryotic cell, on the other hand, has distinct, membrane-bound organelles.

Using a Biological KeyThe steps are written out in a Biological Classification Key. One of the living things we used a Biological Key to classify was a tiger. Begin by determining if something is microscopic, or macroscopic (visible w/ the naked eye). We can see the tiger without the aid of a microscope, so the tiger is macroscopic. To the right of the word microscopic is the number 3. So we skip to question #3.3. Autotrophic or heterotrophic? A tiger cannot make it's own food (like plants can, for example), so it is heterotrophic. To the right of heterotrophic, we see the number 5. So we skip to #5.5. Decomposer or Consumer? A tiger is a consumer of food, not like fungi which is a decomposer. To the right of the word "consumer" are the words "kingdom Animalia" and the number 6.That is our first classification, so in their notebook, the kids wrote the kingdom: "Animalia" and moved on to question 6.6. Backbone or no backbone? Tigers have backbones, and that gives us our next classification of phylum: Chordata. They write it in their notebooks, and we see we should go to number 22.22. Jaws or beak, or no jaw or beak? Tigers have a jaw, and the next number we go to is 23.23. Skin covered with scales or no scales on skin? No scales on skin, so we go to 26.26. No scales, no hair, no feathers; skin is slimy, orfeathers or hair. Tigers have hair; we go to 28, which further distinguishes between hair and feathers.28. Hair or feathers? They have hair, and that means our next classification is class: Mammalia. Write that in the notebook and next is 29.29. Hooves or no hooves? No hooves; go to 31.31. Carnivore or herbivore? What do you think? Carnivore! On to 32.32. Teeth or no teeth? (like an insect.) Tigers have teeth, so the next classification is order: Carnivora.This is the last one for this key, since the key we are using only goes thru kingdom, phylum, class, order.Our classification for a tiger is: kingdom: Animalia; phylum: Chordata; class: Mammalia; order: Carnivora.

Learning how to use a microscope is not as easy as one might think, and it is why high school students are expected to take biology with a lab. What do you do if you do not own or can't afford a microscope? The next best thing is a virtual microscope. Either way, students need to learn the name of each part, and the basics of how to focus. The most classic beginning microscope lab assignment is to look at a cheek cell. It is pretty fascinating to see a cell from your own body.